floor void sleeper wall access / lintels

I am looking at insulating my ground floor in a 1930’s house, which has a suspended timber floor. I plan to install 75 or 100mm rigid insulation between the 4 inch joists resting on battens (I believe there is no need for a vapour barrier).

Last night I opened up the floor void in one of the rooms to find out how big the floor void is and what condition the void area was in.

Thankfully it’s a pretty deep void (36cm clear under the joists), dry and joists are in good condition, there are clear air bricks In the external walls and ventilation is good.

What surprised me was the amount of sleeper walls in the one room I looked at, in a 3.5 x 4m room there are 3 sleeper walls (across the 3.5m).

The size of the void means that I can get under the floor and insulate from below, which is a relief as I don’t want to be pulling up all the boards.

However what I do with all the sleeper walls I have to go through is a concern and I need advice on.

I plan to put an access / hatch in the cupboard under the stairs which is in the centre of the house, and access each room from this location. Getting access to each room by going through sleeper walls under the doorways to each room (not under load bearing internal walls!), and then through the sleeper walls in each room.

I want to make the access permanent so that I can get access easily in the future, so I am thinking that I put a concrete lintel above the new accesses (40cm wide).

The sleeper walls are 4 bricks high so where I put the access I would remove the bricks and put a lintel over the top (DPM between lintel and joist).

http://www.diy.com/departments/expa...d-concrete-lintel-l600mm-w100mm/150789_BQ.prd

Would I need to do this in all access holes, or could I just limit it to the doorways (assuming floor access holes under different joists)?

Thoughts and suggestions?
WN

white_noise, Hi.

The access point you propose makes eminent sense.

As for using the doorways as a route, yes, but as you point out, the joists have to be running parallel to the walls and the joists generally do not run under a door opening.

As for depth??? it is a wee bit tight, OK it is dry and ventilated, but tight?

Accessing the under-floor areas as proposed is a quantum leap better than ripping up the flooring.

What is your proposed insulant? do not try Glass wool!!! in such confined conditions you would need to tape off at ankles, wrists, neck and take massive face / eye protection, not what you need if you are under a floor? OK the void is vented, you simply put are not, if you get my drift??

A solid type of Insulant appears to be the answer, go down, measure the width between joists, return cut several widths of the Insulant then return under to fit it?

As for Lintels? in general terms as long as the lintel has a suitable bearing, at least 100mm each side It should be OK?

Where practicable use the door openings as the access points into the numerous spaces.

Ken

KenGMac said:

What is your proposed insulant?

A solid type of Insulant appears to be the answer, go down, measure the width between joists, return cut several widths of the Insulant then return under to fit it?

As for Lintels? in general terms as long as the lintel has a suitable bearing, at least 100mm each side It should be OK?

Where practicable use the door openings as the access points into the numerous spaces.

Ken

Click to expand...

i am finally getting round to do this job! thanks for your suggestions.

I am going to use 100mm PIR board, and will do as you suggest as measure up first and do the main cutting above ground.

Yep i am going to go through the door openings, and put a 900mm concrete lintel above (probably overkill as timber would be o.k).

Cheers
WN